Wafers of Sn-doped material were etched by means of reactive ion beam etching, using a N/O gas mixture, at ion energies ranging from 100 to 600eV. The radiation damage that was caused by reactive ion beam etching was investigated by using various techniques which were sensitive to the near-surface region. The properties of the damaged layer were studied, as a function of ion energy, by means of photoluminescence microscopy, photoluminescence spectroscopy, spectroscopic ellipsometry and electrochemical capacitance-voltage profiling. The electron channelling pattern technique was used to monitor structural disorder. The observed radiation damage was attributed to the formation of P vacancies; thus indicating a preferential loss of P. The optimum etching conditions involved an ion energy of 400eV, and provided an optimum trade-off between high etching rate and low radiation damage.

H.Iber, S.Mo, E.Peiner, G.Vollrath, A.Schlachetzki, F.Fiedler: Semiconductor Science and Technology, 1997, 12[6], 755-9